[1] Univ Calif San Francisco, GW Hooper Fdn Labs, Dept Microbiol & Immunol, San Francisco, CA 94143 USA
[2] Univ Calif San Francisco, Dept Biochem, San Francisco, CA 94143 USA
[3] Univ British Columbia, Biotechnol Lab, Vancouver, BC V6T 1Z3, Canada
[4] Univ British Columbia, Dept Microbiol & Immunol, Vancouver, BC V6T 1Z3, Canada
[5] Onyx Pharmaceut, Richmond, CA 94806 USA